At issue is whether these veterans are suffering from mental illnesses.

According to a 2013 Senate report, the Department of Veteran Affairs is responsible for reporting more than 143,000 beneficiaries, including about 83,000 veterans, to the “mental defective” category of the National Instant Criminal Background Check System.

Any federal agency can report people to the National Instant Criminal Background Check System, but the VA's recommendations account for about 99 percent of the people who are listed in the mental defective category.

Being listed blocks veterans from purchasing guns.

However, Grassley claims many of these veterans should not be precluded from owning guns.

The VA recommends many military veterans who it deems “incompetent” and in need of financial assistance to manage their benefits be placed in the “mental defective” category of the national gun ban list.

But Grassley says the VA doesn’t actually consider “whether a veteran is a danger to himself, herself, or others,” which is the federal standard for denying someone a gun.

There is a “real possibility that the right to firearms will be infringed,” he said.

“It’s disturbing to think that the men and women who dedicated themselves to defending our freedom and values face undue threats to their fundamental Second Amendment rights from the very agency established to serve them,” Grassley wrote.

“A veteran or dependent shouldn’t lose their constitutional rights, because they need help with bookkeeping,” he added.